Here is a question for you guys who know much more than I about FE motors. I have been reading for a long time here on the boards of how much better a 390 build is than a 360. Before becoming a Ford truck owner I had chevys and the common practice to increase speed out of the chute was to put ( in a mouse motor) a 282 crank into a 327 to produce a 302. There was less c.i. but the shorter stroke made the motor had quicker throttle response, would rev higher and would produce similar numbers in the torque ratings. BUT it was considered a hotter motor than a 327 though having less ci. Now for the BB Ford application. Why did For cut back the 390 to the 360 in its truck aplications? Was this a consideration?
Why is it that the 360 cannot match or even outperform the 390 in a quarter, with its shorter stroke and same size pistons? I have both a 390 and a 360 and am going to be rebuilding one of them but have come up with these questions, which is surprising since I always assumed that the 390 would be the one to rebuild and not the 360. Anyone able to share some light on situation?

 

Ford didn't really "cut back" the 390 to the 360 for trucks. Rather, the FE originally offered in trucks was the 352. In 1968, apparently as a cost saving measure, Ford eliminated the 352 and replaced it with the 360. The 360 and 390 share the same block and bore diameter, and the 390 was being used in passenger cars, so replacing the 352 with the 360 meant one less part Ford had to build and inventory.

At the same time (1968), Ford decided that there was a market for a more powerful truck engine than the 352/360. 390 parts were plentiful, the 390 was well known from its car applications, and it was a direct bolt-in replacement for a 352/360, so Ford decided to start offering the 390 along with the 360. Just a year and a half later (mid '69), Ford also started offering the 302 small block V8, but that's another story.

Why won't a 360 outperform a 390? Well, the simple answer is, "it might." A well-built 360 may outperform a mediocre 390. The 390 has some inherent advantages, however, the most obvious of which being 30 more cubes ("there's no replacement for displacement"). Of course, the 390 also benefits from the torque multiplication effect that comes with having a longer stroke.

It is true that a longer stroke results in higher piston speeds and, typically, more rotating mass, so throttle response tends to suffer in comparison. That's part of the reason that a 427 (4.23 x 3.78) is a much better performance engine than a 428 (4.13 x 3.98) despite the nearly identical displacements. The 428 develops better torque and power down low, but the 427 will rev faster and higher.

On the 360, also, the rods are weak when compared with 390 rods, and the pistons are tall, full skirt jobs. My guess is that 360 pistons typically weigh a lot more than the shorter, slipper-skirt 390 pistons, so the savings from the theoretically lighter crank of the 360 is offset by the heavier pistons.

If you wanted to build a high-rpm "screamer", you might have more success with a 360 than a 390. If you want a high rpm engine in that displacement range, however, why not build a 351? Heck, you could destroke a 427 with a 352/360 crankshaft to make a short stroke 393 cid FE. For trucks, though, the long stroke 410 and 428, or the medium stroke 390, make much better choices.

 

Thanks for the information on the motors. I have been down under the truck in the rain getting the 390 ready to pull to rebuild. One thing of interest here is that one of the problems I have had with the motor is that there was an annoying ticking sound that sounded like a valve lifter but was sounding to be deeper in the motor. I figure that a rebuild will correct the noise. BUT as I was preparing it to pull I took off the inspection plate to remove the tc nuts. What I found was the the nuts looked like they have been hitting something that was causing them to shread and there was metal particles around the nuts on the flywheel. I wonder if this could be the source of my mystery noice, but I have no idea where it could be hitting. I guess I'll find out when I pull the motor. I may find the motor sound and the noise was transmission related. Oh well, I figure it was due a rebuild anyway. Just thought I'd share this quandry. BTW, only two of the four were affected by hitting something. Makes me wonder if the flywheel may have a problem. IN an another vien, I was trying to clean the many ac and power steering pump brackets and started to wonder if I'll get them back in the correct order when I reassemble. Is there a schematic on how the brackets are reattached? I hope I can remeember but just in case, any resource will be helpful. Thanks for your thoughts.
Billy